Frustrated-total-internal-reflection multimode fiber-optic hydrophone.

A multimode fiber-optic hydrophone based upon the principle of frustrated total internal reflection has been constructed and tested. The sensitivity of the device to acoustic waves in water is in good agreement with predictions derived from its measured sensitivity to applied static displacements in air. The minimum detectable pressure for the device was 62 dB relative to 1 micro Pa at 500 Hz. Static displacements as small as 4.8 x 10(-3) A can be detected. The sensor is compatible with present multimode fiber-optic sources, detectors, and components.